Hydraulic lash adjuster



March 19, 1957 R. K. EVANS HYDRAULIC LASH ADJUSTER 2 Sheets-Sheet 1 Filed Jan. 20, 1955 IN ENTOR fia/mfiziKz/azzs BY 87%.. AT TORNEY United States HYDRAULIC LASH ADJUSTER Application .lanuary 20, 1955, Serial No. 482378 17 Claims. (Cl. 123-90) This invention relates to poppet valve operating mechanisms for internal combustion engines and the like utilizing rockers for transmitting valve opening and closing movements to and from the valve, and particularly to a mounting for such a rocker which automatically adjusts its fulcrum to compensate for wear and other factors tending to affect the lash or operating clearance between the rocker and other parts drivingly associated with it.

One of the principal objects of the invention is to improve such mechanisms by arranging the rocker to be carried by a stud extending through it from the engine cylinder head or other fixed part of the engine, the engine end of the stud carrying a plunger whose movement toward the rocker is cushioned by a body of oil in a dash pot rigid with the cylinder head.

Additional objects of the invention are to provide an improved lash adjuster adapted for mounting a rocker in the aforementioned manner, and to provide a novel means of supplying engine lubricating oil to the oil cushion chamber of such a lash adjuster.

The means by which these and other objects of the invention are attained will be clearly apparent from the following description, having reference to the drawings wherein:

Figure l is a transverse view through a portion of a V-type internal combustion engine incorporating a rocker hydraulic lash adjuster mechanism in accordance with the invention.

Figure 2 is an enlarged cross-sectional view of the lash adjuster mechanism and certain of its associated engine parts as shown in Figure 1.

Figures 3, 4 and 5 show successive modifications of the lash adjusting mechanism.

Referring in detail to Figures 1 and 2 of the drawings, there is shown an engine frame member including a crankcase 1 of conventional V-type having a cylinder head for each bank, one of which is indicated at 2. An engine driven cam 3 drives the tappets 4, each of which is connected by a push rod 5 and a valve rocker 6 to actuate a poppet valve 7. As shown, the rocker 6 is of upwardly dished configuration and has its respective ends overlying the upper ends of the push rod 5 and the stem of the valve 7, each of which protrudes above the cylinder head 2. The dished shape of the rocker serves to conduct engine lubricating oil fed to it through the push rod and tappet which are made hollow for this purpose, the tappet being slidably mounted in the crankcase and having registering openings 4' communicating with the oil pressure gallery 8. The upper end of each push rod has a port 9 registering with the port 10 extending through the end of the rocker, and intermediate its push rod end and the stem of the valve 6 the rocker is provided with a spherical bearing. surface 11 to which the oil flows from the port 10. Excess oil is normally supplied through the push rod in the manner stated so as to overflow the valve end of the rocker and effect lubrication of its valve actuating surface 12. Centrally of the rocker bearing surface 11 is an atent aperture 13 through which extends a stud 14 having a rocker journalling member 15 secured at its upper end by suitable means such as a nut 16. The lower face of the journalling member 15 is also made spherical to conform with the rocker bearing surface 11, except a relief groove 17 may be provided in the journalling member to ensure a substantial drainage of oil through the rocker aperture 13 during operation. The valve 7 has its stem reciprocally guided in the cylinder head to open with each lift stroke of the cam 3, there being the usual valve return spring 17' secured to the upper end of the valve stem and reacting against the cylinder head.

As best shown in Figure 2, the cylinder head is provided with an internally threaded opening 18 below the rocker, and screwed into this opening is a dash pot in the form of a generally upright cup-shaped cylinder 19 into which the lower end of the stud 14 extends. The bore 29 of this cylinder is substantially larger than the periphery of the stud whereby a pressure chamber 21 is formed between them. Slidably fitting this bore 20 and defining the lower end or" the pressure chamber 21 is a plunger 22 formed in part by an upright cup-shaped member whose end wall 23 is apertured to embrace the stud 14 and which rests on a flange 24 formed on the lower end of the stud. Completing the plunger 22 is a gasket 25 which seals against the escape of oil between the plunger member end wall 23 and the flange 24. The stud 1-; does not extend into abutment with the cylinder end wall 26 but is separated axially therefrom to provide an oil reservoir 27 between them. A guide sleeve 28 slidably supports the stud 14 within the cylinder and is, in turn, supported by a flange 29 on this guide sleeve which overlies the open end of the cylinder. A gasket 30 may be provided between this flange and the cylinder open end, as shown, for sealing purposes at this point..

The guide sleeve is secured against movement outwardly of the cylinder by a hollow nut 31 which is screwed on to the threaded upper end of the cylinder and has a shoulder 32 which clampingly engages the guide sleeve 29. This flange 29 also constitutes a wall defining theupper end of the pressure chamber 21, and has an oil passage 33 extending through it and counterbored at its.

partially underlie the counterbored lower end of the passage 33 and serve as a retainer limiting opening travel of the ball check valve 34. The upper face of the guide sleeve flange 29 is relieved by a transverse slot or groove 37 which connects the upper end of the passage 33 with the periphery of the stud 14. The interior of the hollow nut 31 above the guide sleeve flange 29 forms an upper oil reservoir 33 into which oil is received by drainage through the rocker opening 13. An annular filter element 39, pressed into the hollow nut against the flange 29, is provided to prevent any foreign particles being carried into the groove 37 with the oil draining from the rocker. The upper and lower reservoirs 33 and 27 are interconnected by longitudinally and transversely drilled passages 49 and 41 in the stud 14, with registry of the transverse passages 41 with the groove 37 at all times being ensured by an annular groove 42 encircling the stud at this point;

During operation, with each lift stroke of the cam 3 its motion is transmitted through the tappet 4, push rod 5 and rocker 6 to open the valve against the valve return spring 17. The resultant upward thrust of the rocker against its journalling member 15 tends to move the stud 14 outwardly of its cylinder 19. Although this movement.

member, a dash pot rigid with the frame member, plunger means operable in said dash pot having a portion extending through the rocker in a direction transverse to the rocker fulcrum axis, coacting bearing surfaces on the rocker and the extended portion of the plunger, a passage for introducing fluid into said dash pot, a resilient member biasing said plunger means outwardly of said dash pot, and a check valve accommodating flow of fluid through said passage in the direction inwardly of the dash pot and preventing flow therethrough in the opposite direction.

2. In a support for a rocker having an aperture extending therethrough normal to its fulcrum axis, a stud adapted to extend through said aperture and accommodate the oscillatory movement of the rocker to be supported, said stud having a bearing surface adjacent one of its ends' for journalling said rocker movement, the opposite end of said stud having a plunger fixed thereon, a cylinder slidably supporting said plunger and defining a fluid pressure chamber adjacent the rocker side of the plunger, means including a one-way valve controlled passage for supplying fluid to said chamber, a wall defining the extremities of said chamber nearest the rocker, and a spring biasing the plunger in the direction away from said wall.

3. In a valve operating mechanism for an engine or the like, a rocker, supporting means for the rocker including a fixed engine frame member, a cylinder fixed to the frame member having its axis generally normal to the fulcrum axis of the rocker, a transverse wall fixed to the cylinder and cooperating with the side walls thereof in defining a fluid pressure chamber, a plunger slidably fitting the cylinder side walls and defining the end of said chamber remote from said transverse wall, said transverse wall having an opening, said plunger having a stud portion extending through and closely fitting said opening, said rocker having an aperture loosely embracing the stud portion with sufficient clearance to accommodate rocking movement of the rocker during valve opening and closing, a bearing on the stud portion journalling the rocker in its rocking movement, a compression spring in said chamber interposed between said transverse wall and said plunger, said cylinder having a portion intermediate said transverse wall and the frame member cooperating with said stud portion in defining a fluid reservoir, a passageway connecting said reservoir and chamber, and a valve operative to open and close said passageway in response to decreased chamber fluid pressure resulting from movement of the plunger by the spring and increased chamber fluid pressure resulting from movement of the plunger against the spring, respectively.

4. In a valve operating mechanism for an engine or the like, a rocker, supporting means for the rocker including a fixed engine frame member, a cyhnder fixed to the frame member having its axis generally normal to the fulcrum axis of the rocker, a transverse wall fixed to the cylinder and cooperating with the side walls thereof in defining a fluid presure chamber, a plunger slidably fitting the cylinder side walls and defining the end of said chamber remote from said transverse wall, said transverse wall having an opening, said plunger having a stud portion extending through and closely fitting said opening, said rocker having an aperture loosely embracing the stud portion with sufiicient clearance to accommodate rocking movement of the rocker during valve opening and closing, a bearing on the stud portion journalling the rocker in its rocking movement, a compression spring in said chamber interposed between said transverse wall and said plunger, said cylinder having a portion on the opposite side of the plunger from the rocker defining a first fluid reservoir and a portion intermediate said transverse wall and the rocker defining a second fluid reservoir, a passageway connecting said second reservoir and chamber, a valve at the chamber end of said passageway movably responsive in an opening direction to the fluid pressure in the second reservoir and in a closing direction to the fluid 6 pressure in the chamber, and a passageway connecting said first and second reservoirs'for transferring fluid therebetween in response to relative axial movements of the plunger and cylinder.

5. The invention defined in claim 4, together with a source of fluid under pressure and driving means for said rocker including a hollow push rod in fluid communication with said source, said rocker and push rod having coacting bearing surfaces with mutually registering ports and a passageway in said rocker connecting its said port with its said aperture.

6. The combination with an engine cylinder head and a poppet valve operating train including a valve stem reciprocable in the head and a reciprocably driven push rod, both terminating above the head, a rocker mechanically interconnecting the push rod and valve stem, and rocker mounting means including a stud extending through the rocker from the cylinder head, of means for thrustably supporting and axially adjusting said stud relative to the cylinder head to automatically compensate for changes in the operating length of said train, said last named means including a generally cup-shaped engine oil receiving member fixed to the cylinder head and having a bore embracingthe cylinder head end of said stud, plunger means on said stud slidably fitting said bore, an annular member fixed to said cup-shaped member below the open end thereof and slidably fitting the stud above said plunger means, said annular member having an oil passage therethrough connecting the interior of said bore above the plunger means with the interior of the cup-shaped member above the annular member, a check'valve at the bore end of said passage preventing oil flow therethrough from below the annular member while accommodating flow in the opposite direction, a spring compressed between said plunger means and annular member for urging the stud toward the cylinder head.

7. The combination with an engine cylinder head and a poppet valve operating train including a valve stem reciprocable in the head and a reciprocably driven push rod, both terminating above the head, a rocker mechanically interconnecting the push rod and valve stem, and rocker mounting means including a stud extending through the rocker from the cylinder head, of means for thrustably supporting and axially adjusting said stud relative to the cylinder head to automatically compensate for changes in the operating length of said train, said last named means including a generally cup-shaped engine oil receiving member fixed to the cylinder head and having a bore embracing the cylinder head end of said stud, a flange on the cylinder head end of the stud, a cup-shaped plunger embracing the stud above said flange and slidably fitting said bore, a guide sleeve slidably fitting the stud above said flange and extending into said plunger, said guide sleeve having a flange at its upper end overlying the upper end of said cup-shaped member, a hollow nut screw threaded to the upper external periphery of the cup-shaped member and clamping said guide sleeve flange to the upper end of said cup-shaped member, a coil compression spring embracing said guide sleeve and seated at its opposite ends against the end wall of the plunger and said guide sleeve flange, said guide sleeve flange having. an oil passage therethrough connecting the interior of said bore above the plunger with the interior of the hollow nut above the guide sleeve flange, a check valve at the bore end of said passage preventing oil flow therethrough from below said guide sleeve flange while accommodating flow in the opposite direction, and an annular filter extending between the external periphery of the stud above said guide sleeve flange and the internal periphery of said nut through which engine lubricating oil may be introduced to the upper end of said passage.

8. In a hydraulic valve lash adjuster for an over-head valve type internal combustion engine or the like having a valve rocker mounted on a stud extending through the rocker from the head, a rocker mounting stud having a a 7 plunger part fixedthereto adjacent the head end of the stud, 'a' cylinder'part slidably supporting the plunger and havin'ghrst: and second portions cooperating respec- ,tively therewith'to define an oil cushion chamber between theplunger part and the rocker and a reservoir for 'oil to be supplied to said chamber, a spring biasing the plunger'part "in the direction to enlarge said charrl ber, passage means, providing for fiow of oil from said reservoir to said chamber, and a check 'valve operative in response to increased pressure in said chamber result ing from plunger movement against said spring to prevent said oil flow.

9, The invention defined in claim 8, wherein said cylinder part and stud have slidably interfitting surfaces between said chamber and the rocker defining a leakage path for oil escaping from the chamber, said stud hating an oil leakage collecting groove in its said surface and a passage connecting said groove with said reservoir.

10; The invention defined in claim 9, wherein said cylinder part includes a wall defining the rocker end of said chamber and having a skirt portion depending into said chamber and defining the said cylinder part surface, said wall having an opening extending therethrough longitudinally of the stud and defining in part said passage means, said check valve being located at the chamber end or" said opening. a

11. In combination with an engine cylinder head having an opening therethrough for a poppet valve stem to be operated by a rocker spaced above the cylinder head, and a second opening laterally spaced from said first opening, said second opening being internally threaded, ani upwardly open dash pot member having a reduced lower portion with external threads engaging said inter? nal threads and a shoulder'seated against the upper surface of the head surrounding said second opening, said dash pot having an axially extending bore and an upwardly presenting internal shoulder above said bore, a fixed guide sleeve in said dash pot spaced radially from said here and'having an external flange sealingly engaging said shoulder, a stud slidably fitting said sleeve on the stud above the rocker, bearing means on'the rocker adjacent said opening engaging said journalling means, a compression spring within said bore and reacting against said flange, a plunger on said stud slidably fitting said bore and biased by said spring in the direction away from the rocker, means for introducing hydraulic fluid to the space within said bore between said plunger and flange, saidmeans including a passage through saidfiange, and a check valve at the inner end of said passage.

, 12. In, combination with a rocker drivingly connected to oppositely reciprocating elements extending from one side thereof, rocker supporting means including a memberfon the opposite side journalling the rocker for oscillation about its fulcrum'axis and a hydraulic lash adjuster located on said one sidefof the rocker between said elements, said lash adjuster including a hydraulically cushioned member thrustably supporting said journalling member. 7 v

13. In combination with a rocker for transmitting motion between oppositely reciprocating driving and driven. elements, rocker supporting means including a memberon one side of the rocker journalling the rocker for oscillation about its fulcrumaxis and a hydraulic lash adjuster located on the opposite side of the rockerj from said member, said lash adjuster including a h ydraulic' cushion chamber and'a plunger member in said chamber having a portion extending through the rocker able member biased fromthe fixed member, said journalling member being carried by said movable member.

15. in combination with a rocker having an opening, extending therethrough in the thrust direction, supporting and journaliing means for the rocker including a member defining a dash pot, a plunger member operable in said dash pot having a portion extending through said. opening, one of said members being fixed, said rocker. and the other of said members having coacting bearing surfaces defining the rocking axis of the rocker, and one: way passage means for introducing hydraulic fluid into said dash pot behind the plunger member.

16. In combination with a rocker having an opening extending therethrough in the thrust direction, supporting and journalling means for the rocker including a fixed support, a first member extending through said opening with sufilcient clearance to accommodate rocking movement of the rocker, a second member tele scopically associated with said first member, said members having endwise facing surfaces defining a fluid pressure chamber therebetween, one of said members being anchored to said support, said rocker and the other of said members having coactingbearing surfaces defining the-rocking axis of the rocker, and one-Way passage means for introducing fluid into said pressure chamber,

17. Supporting and journalling means for a rocker of the stud mounted type which has an opening extending therethrough in the thrust direction, comprising a first member provided with a surface defining one end of a fiuid pressure chamber and having a studportion extend-t ing generally normal to said surface forpassage through, said opening, a second member telescopically associated. with said first member and defining the opposite end of said chamber, one of said members having a bearing surface adapted to journably engage the rocker adjacent said opening and define the rocking axis of the rocker,

the other of said members havingsurfaces slidably sup porting said one member for movement axially of said: stud portion, and passage means for introducing fluid into said chamber and restricting its return therefrom.

References-Cited in the file of this patent UNITED STATES PATENTS 1,741,678 Brewer Dec. 31, 1929- 1,797,105 Shoblom Mar. '17-, 193i 1,937,932 Woolm an Dec. 5, 1933- 2,075,597 1 Zahodiakin Mar. 30, 1937 2,158,222 Dayton 'May 16, 1939 2,572,968 Bachle Oct; 30, 1951 2,669,981 Leach; .Feb. 23, 1954 FOREIGN PATENTS 436,744 Great Britain 0a.;17, 193-5 

